Inverting homotopy groups of spectra
Let $X$ be a spectrum. Is there a canonical construction/functor that would associate to this spectrum, an inverse spectrum $X'$, in the sense that $$pi_*(X)cong pi_{-*}(X')?$$
To be more precise, such a spectrum $X'$ can always be constructed by attaching cells to produce the right homotopy groups, but is there a more conceptual way of creating it?
at.algebraic-topology stable-homotopy
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Let $X$ be a spectrum. Is there a canonical construction/functor that would associate to this spectrum, an inverse spectrum $X'$, in the sense that $$pi_*(X)cong pi_{-*}(X')?$$
To be more precise, such a spectrum $X'$ can always be constructed by attaching cells to produce the right homotopy groups, but is there a more conceptual way of creating it?
at.algebraic-topology stable-homotopy
add a comment |
Let $X$ be a spectrum. Is there a canonical construction/functor that would associate to this spectrum, an inverse spectrum $X'$, in the sense that $$pi_*(X)cong pi_{-*}(X')?$$
To be more precise, such a spectrum $X'$ can always be constructed by attaching cells to produce the right homotopy groups, but is there a more conceptual way of creating it?
at.algebraic-topology stable-homotopy
Let $X$ be a spectrum. Is there a canonical construction/functor that would associate to this spectrum, an inverse spectrum $X'$, in the sense that $$pi_*(X)cong pi_{-*}(X')?$$
To be more precise, such a spectrum $X'$ can always be constructed by attaching cells to produce the right homotopy groups, but is there a more conceptual way of creating it?
at.algebraic-topology stable-homotopy
at.algebraic-topology stable-homotopy
edited Dec 22 at 18:24
David White
11.5k460100
11.5k460100
asked Dec 22 at 16:56
user09127
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Not exactly what you asked for, but there is the Brown-Comenetz dual of $X$, $I_{mathbb{Q}/mathbb{Z}}X$, which has the property that its homotopy groups are Pontryagin dual to the homotopy groups of $X$ (in the negative degree):
$pi_{-ast}(I_{mathbb{Q}/mathbb{Z}}X) simeq Hom(pi_ast(X),mathbb{Q}/mathbb{Z})$
So, if the homotopy groups of $X$ are all finite, then the Pontragin dual groups will be (non-canonically) isomorphic and this will have the required property.
See here for more details
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
add a comment |
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1 Answer
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1 Answer
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votes
Not exactly what you asked for, but there is the Brown-Comenetz dual of $X$, $I_{mathbb{Q}/mathbb{Z}}X$, which has the property that its homotopy groups are Pontryagin dual to the homotopy groups of $X$ (in the negative degree):
$pi_{-ast}(I_{mathbb{Q}/mathbb{Z}}X) simeq Hom(pi_ast(X),mathbb{Q}/mathbb{Z})$
So, if the homotopy groups of $X$ are all finite, then the Pontragin dual groups will be (non-canonically) isomorphic and this will have the required property.
See here for more details
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
add a comment |
Not exactly what you asked for, but there is the Brown-Comenetz dual of $X$, $I_{mathbb{Q}/mathbb{Z}}X$, which has the property that its homotopy groups are Pontryagin dual to the homotopy groups of $X$ (in the negative degree):
$pi_{-ast}(I_{mathbb{Q}/mathbb{Z}}X) simeq Hom(pi_ast(X),mathbb{Q}/mathbb{Z})$
So, if the homotopy groups of $X$ are all finite, then the Pontragin dual groups will be (non-canonically) isomorphic and this will have the required property.
See here for more details
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
add a comment |
Not exactly what you asked for, but there is the Brown-Comenetz dual of $X$, $I_{mathbb{Q}/mathbb{Z}}X$, which has the property that its homotopy groups are Pontryagin dual to the homotopy groups of $X$ (in the negative degree):
$pi_{-ast}(I_{mathbb{Q}/mathbb{Z}}X) simeq Hom(pi_ast(X),mathbb{Q}/mathbb{Z})$
So, if the homotopy groups of $X$ are all finite, then the Pontragin dual groups will be (non-canonically) isomorphic and this will have the required property.
See here for more details
Not exactly what you asked for, but there is the Brown-Comenetz dual of $X$, $I_{mathbb{Q}/mathbb{Z}}X$, which has the property that its homotopy groups are Pontryagin dual to the homotopy groups of $X$ (in the negative degree):
$pi_{-ast}(I_{mathbb{Q}/mathbb{Z}}X) simeq Hom(pi_ast(X),mathbb{Q}/mathbb{Z})$
So, if the homotopy groups of $X$ are all finite, then the Pontragin dual groups will be (non-canonically) isomorphic and this will have the required property.
See here for more details
edited 2 days ago
answered Dec 22 at 17:37
Sam Gunningham
4,3571929
4,3571929
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
add a comment |
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
There's a question that always bothered me. Maybe you know the answer. How canonical is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$? More precisely, is the assignment $Xmapsto I_{mathbb Q/mathbb Z}X$ a functor from the $infty$-groupoid of spectra to itself? It's obviously a functor at the level of the homotopy category. But what about at the $infty$-groupoid level?
– André Henriques
2 days ago
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@AndréHenriques I've probably misunderstood your question, but does this answer it? If $I_mathbf{Q/Z} := I_mathbf{Q/Z}(S^0)$ denotes the Brown-Comenetz dualizing spectrum, then $I_mathbf{Q/Z}(X) = F(X, I_mathbf{Q/Z})$, and this is functorial in $X$.
– skd
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
@skd. Yes, of course... that does answers my question. But I now realise that I haden't asked the right question. Here's the right question: what is $I_{mathbb Q/mathbb Z}$? More precisely, is there a way to define it up to contractible space of choices?
– André Henriques
yesterday
add a comment |
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